1. Technical Field
This application relates to a medical guidewire and more particularly to a medical guidewire system with adjustable size and stiffness.
2. Background of Related Art
Guidewires are currently being used in medical procedures to guide catheters, sheaths or other devices from a remote site to a surgical site. From a remote part of the body, a guidewire is introduced into an artery or vein. The guidewire is then advanced through the vascular system to the target site where an angiogram, balloon, stent, catheter or other vascular device is to be positioned. The guidewire then functions as a rail for advancement of these devices.
Currently, a soft small diameter wire, such as a 0.014 wire, is utilized initially to advance in the artery or vein. During advancement, especially through tortuous anatomy, the soft wire may lack the requisite pushability to advance around a curve. Also, due to its softness/flexibility, it may be difficult to advance a catheter over it to perform the surgical, e.g. diagnostic and/or interventional, procedure. In these instances, this flexible wire needs to be exchanged for a stiffer and/or larger wire. To exchange the guidewire, several steps are required. First, an exchange catheter is advanced over the soft wire. Second, the soft wire is removed. Third, the stiffer wire is inserted through the exchange catheter. Fourth, the exchange catheter is removed, leaving the stiffer wire in place. Such wire exchanges are time consuming and require two separate wires and an exchange catheter. Furthermore, these steps also increase risks to the patient such as increased risk of infection and increased chance of damaging the vessel due to the added insertion and removal of the wires through the vascular system as well as possible loss of wire position and critical time loss.
Even after exchange for the larger wire, sometimes the requisite stiffness and pushability to advance through a curved vessel portion is still lacking and therefore the wire needs to be exchanged for yet an even stiffer wire. This requires an additional wire exchange utilizing the time consuming four step method described above.
After such exchange for a stiffer wire and advancement around the tortuous portion of the anatomy, a stenosis or restricted passage of the vessel might be encountered through which the larger wire cannot pass. Thus, yet another catheter exchange could be required, this time exchanging the larger diameter stiffer wire for the smaller diameter softer wire. As a result, multiple guidewire exchanges requiring multiple insertions of the exchange catheter, multiple removals of the already inserted wire, and multiple insertions of a new wire from the remote site may be necessary in a single surgical (diagnostic and/or interventional) procedure. As noted above, this adds undesired time to the surgical procedure, as well as increases the risk of trauma or damage to the vessel and loss of desired wire position.
In addition, the inventor has found that in some instances where a catheter exchange is required, the surgical procedure cannot even be performed. That is, in some instances, the exchange catheter, which has a larger diameter (typically about 0.040 inches inside diameter) than the stiffer replacement wire because it has a lumen to receive the wire, cannot cross the stenosis. In this case, the guidewire with increased pushability cannot be inserted and advanced to reach the target site, thus not enabling a stent, dilation balloon or other vascular treatment device to be advanced to the surgical site. Consequently, the intralumenal surgical procedure cannot be performed.
As can be appreciated from the above, in the current procedure, multiple guidewires may be required to achieve desired parameters such as softness to reduce trauma to the vessel during insertion, reduced diameter to enable access through restricted passages in the vessels and facilitate access to the surgical site, stiffness/rigidity to allow pushability and stiffness/rigidity to facilitate passage of a catheter thereover. For example, a gentler more flexible guidewire, such as a 0.014 inch diameter wire, has the small diameter and softness advantage, but lacks the pushability to advance through some tortuous anatomy. The larger diameter guidewire, such as the 0.035 or 0.038 inch diameter guidewire, is more rigid and has better pushability but may be too large for restricted passages. It may also still lack the necessary stiffness, thus requiring an exchange for an extra stiff wire. The extra stiff wire lacks the flexibility and softness. Thus, the user needs to exchange the wires to obtain the requisite pushability, flexibility and stiffness for accessing the diagnostic and/or interventional site.
Also, exchange sheaths, when used with a 0.014 guidewire, present a relatively large stepped transition from their distal end to the smaller diameter 0.014 guidewire, therefore creating a more traumatic “snow plow” effect during insertion.
Therefore, it would be advantageous to provide a guidewire system which provides the desired diameter, pushability, flexibility and stiffness without requiring guidewire exchanges and exchange catheters, thereby eliminating the foregoing disadvantages of such exchanges.
It would also be advantageous if fluid, such as contrast, could be injected through the guidewire system for visualization.